单选题Directions: there are twenty blanks in the following
passage. For each blank there are four choices marked A, B, C and D, You should
choose the ONE that best fits into the passage. Then mark the corresponding
letter on the Answer Sheet. There are three
separate sources of hazard {{U}} {{U}} 1 {{/U}} {{/U}}to the use
of nuclear reaction to supply us with energy Firstly, the radioactive material
must travel from its place of manufacture to the power station {{U}}
{{U}} 2 {{/U}} {{/U}}the power stations themselves are solidly
built, the container used for transport of the material are not. Unfortunately,
there are {{U}} {{U}} 3 {{/U}} {{/U}}only two methods of
transport available, {{U}} {{U}} 4 {{/U}} {{/U}}road or rail,
and both of these {{U}} {{U}} 5 {{/U}} {{/U}}close contact with
the general public, {{U}} {{U}} 6 {{/U}} {{/U}}the routes are
{{U}} {{U}} 7 {{/U}} {{/U}}to pass near, or even through,
{{U}} {{U}} 8 {{/U}} {{/U}}populated areas.
Secondly, there is a problem of wastes. All nuclear power stations produce
wastes which {{U}} {{U}} 9 {{/U}} {{/U}}will remain radioactive
for thousands of years. It is {{U}} {{U}} 10 {{/U}} {{/U}}to
deactive these wastes, and so they must be stored {{U}} {{U}}
11 {{/U}} {{/U}}one of the ingenious but cumbersome ways that scientists
have invented, For example, they must be buried under the ground {{U}}
{{U}} 12 {{/U}} {{/U}}sunk in the sea. However, these {{U}}
{{U}} 13 {{/U}} {{/U}}do not solve the problem completely, they
merely store it, since an earth-quake could {{U}} {{U}} 14
{{/U}} {{/U}}open the containers like nuts. Thirdly, there is
the problem of accidental exposure {{U}} {{U}} 15 {{/U}}
{{/U}}to a leak or an explosion at the power station. {{U}} {{U}} 16
{{/U}} {{/U}}with the other two hazards, this is not very likely and does not
provide a serious {{U}} {{U}} 17 {{/U}} {{/U}}to the nuclear
program, {{U}} {{U}} 18 {{/U}} {{/U}}it call happen, as
the inhabitants of Harrisburg will tell you. Separately,
and during short periods, these three types of risk are no great cause for
concern. {{U}} {{U}} 19 {{/U}} {{/U}}, though, and especially
{{U}} {{U}} 20 {{/U}} {{/U}}much longer periods, the probability
of a disaster is extremely high.